EXHAUST GAS PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

An internal combustion is configured such that a hydrocarbon supply valve (15) and an exhaust gas purification catalyst (13) are arranged in an engine exhaust gas passage and such that NO x contained within exhaust gas is purified by spraying hydrocarbon from the hydrocarbon supply valve (15) at predetermined intervals. When SO x is to be released from the exhaust gas purification catalyst (13), the air-fuel ratio of exhaust gas which flows into the exhaust gas purification catalyst (13) is enriched by generating, within a cylinder, combustion gas having a rich air-fuel ratio, and after that the air-fuel ratio of exhaust gas which flows into the exhaust gas purification catalyst (13) is enriched by supplying hydrocarbon from the hydrocarbon supply valve (15).